With a big enough battery and powerful enough inverter to charge it in a 3-hour window, you could be buying at 6c with Pinergy and selling at 25c. Even with round-trip losses and tax, that’s about a 5-6c profit per unit.
How much are Solar Panels worth
- Thread starter cremeegg
- Start date
Is it actually that low after losses and tax?
So let’s take a 10kwh battery as an example. Usually about 9kwh usable.
Call it 10c profit. That’s 90c a day or €330 a year.
For my set up a battery of that size was about €3k with a 10 year warranty which I think is based on 60% efficiency after 10 years.
I think you would be doing well to get to €3k that way.
Obviously the battery might last another 10 years but unless you are getting the battery a lot cheaper that doesn’t seem like a great plan to me.
The big risk is the FIT drops. It seems mad that you can buy for 9c at 2am and sell for 25c at 4am.
Yeah, the taxation after 2x€400 is at full export price (25c) rather than the difference (25-6c=19c) and then the post I replied to assumed a 52% tax rate on that.
But that’s probably not the only benefit. Every kWh consumed rather than exported is not taxed and so has a higher payback. Even on a second battery, some will be consumed during winter months.
I couldn't quite make the maths work on a second 9kWh. I felt battery 1 would be used to some degree all year around, especially as my panels are south facing so won't get sun first thing in the morning or late into the evening.
However battery two would maybe only be used for maybe 4 months for load shifting and only two months fully.
Then there was the issue of charging it, I have an EV and a two hour EV window at 9c where I heat the hot water, charge the car and the battery obviously. I also sometimes do the dishwasher and washing machine.
Heat Pump: approx 3.5kW
Car: 7kW
Battery: 4.5kW
Wahing Machine / Dishwasher: I think they can spike when heating water at about 3kWh.
The max power I can import is 12kW so I cant run everything at once and will probable move to a plan with 3 or 4 hours but with the second battery I would probable need to be on a day/night rate.
I am open to being wrong on this and will revisit in a year with better data as I just got my system.
CuriousG10
New Member
- Messages
- 4
I'm trying to figure out when the payback would be trying to take everything into account. I know there are loads of variables and a lot of this is guesswork. I switch every year getting best rate available and my bill works out at roughly 1500 per year, I have gas heating , no EV.
Lots of people saying payback in 5 / 6 years which I just cannot see.
I am seeing getting solar panels as purely an investment strategy (A) so going to compare with another investment strategy B where I invest the 9K I would have spent on solar in a fund where I get a 4% return but this fund diminishes as I use this to pay my 1.5K a year bill of electricity.
I have a running total of what my electricity would cost at the end of each year for A and B and the difference between the 2 in the middle.
So A starts with 9K initial solar cost + 300 bill per year (I took standing charge of 260 and a little more???), I also added 100 expenses every 2 years, not sure, its a new piece of kit, things can go wrong, also heard they need to be cleaned so not completely maintenance free.
B has the 1.5K cost less the return from investment. So fund from B runs out after year 7.
But it is after year 10 that I turn a profit. Is this realistic?
And thinking about this as purely an investment, solar panels is the most fixed term investment you can make, no way to get money back if ever needed. If the 9K was put away for a fixed term of 10 years , you would expect to double your money in that time.
Lots of people saying payback in 5 / 6 years which I just cannot see.
I am seeing getting solar panels as purely an investment strategy (A) so going to compare with another investment strategy B where I invest the 9K I would have spent on solar in a fund where I get a 4% return but this fund diminishes as I use this to pay my 1.5K a year bill of electricity.
I have a running total of what my electricity would cost at the end of each year for A and B and the difference between the 2 in the middle.
So A starts with 9K initial solar cost + 300 bill per year (I took standing charge of 260 and a little more???), I also added 100 expenses every 2 years, not sure, its a new piece of kit, things can go wrong, also heard they need to be cleaned so not completely maintenance free.
B has the 1.5K cost less the return from investment. So fund from B runs out after year 7.
But it is after year 10 that I turn a profit. Is this realistic?
And thinking about this as purely an investment, solar panels is the most fixed term investment you can make, no way to get money back if ever needed. If the 9K was put away for a fixed term of 10 years , you would expect to double your money in that time.
CuriousG10
New Member
- Messages
- 4
Yes includes battery, could have added a percentage to bill cost each year but there is also solar panel degradation so even though it does not look like it, I tried to keep it simple.
I know it depends on a lot of factors but does 300 per year sound ok for yearly bill or should I have net zero usage and just use 260 standing charge?
Also the expenses worries me, I cannot see the solar panels sitting up there for 20 years without having some major repair bill at some stage which would wipe out a years profit. Anyone have any experience like this?
I know it depends on a lot of factors but does 300 per year sound ok for yearly bill or should I have net zero usage and just use 260 standing charge?
Also the expenses worries me, I cannot see the solar panels sitting up there for 20 years without having some major repair bill at some stage which would wipe out a years profit. Anyone have any experience like this?
CharlieMac
Registered User
- Messages
- 514
I'm Nobody
Registered User
- Messages
- 111
5 KWh Battery.
South facing.
18 × 435W Jinko Solar Tiger Neo Satin.
Our electricity bill for 2025 €280.
4 bed detached house.
South facing.
18 × 435W Jinko Solar Tiger Neo Satin.
Our electricity bill for 2025 €280.
4 bed detached house.
@CuriousG10 I think you might be perhaps underestimating your solar panel investment gains (or perhaps not maximising the battery investment return potential).
While there are a lot of variables at play and every installation/situation will have their own set but just to look at this in another light...
I have very recently "invested" in a 9.9 kWp South solar system including a 10kWhr battery. Total investment cost of €10k (nett of grant). Our annual electricity costs are < €1000. Maximising the battery investment by load shifting and utilising current FIT levels as well as low charging costs in the wee hours I have calculated a predicted payback period of less than 5 years.
While time will tell of course, in the 1st 10 days of March the system has, between house load offsetting and FIT, 'earned' approx €45 (i.e. we are net €45 better off than if there was no solar install). In those 10 days there were 5 reasonable solar days and 5 duds. Not too shabby but too short a time period to make any conclusions but for a period between the 2 solstices it might be a good indication.
This also buys us an off grid system which will see us through the many power outages (sometimes for days) we experience every year.
I will likely need to replace the inverter within 10 to 15 years so that needs to be taken into account (current cost is ~€1200). There are very few other pieces of kit that will need replacement or servicing I reckon.
While the investment is indeed 'long term fixed' and there is no guarantee of FIT lasting at current or any levels, my view is that a lot of the returns are also guaranteed once the sun rises in the east and sets in the west.
While there are a lot of variables at play and every installation/situation will have their own set but just to look at this in another light...
I have very recently "invested" in a 9.9 kWp South solar system including a 10kWhr battery. Total investment cost of €10k (nett of grant). Our annual electricity costs are < €1000. Maximising the battery investment by load shifting and utilising current FIT levels as well as low charging costs in the wee hours I have calculated a predicted payback period of less than 5 years.
While time will tell of course, in the 1st 10 days of March the system has, between house load offsetting and FIT, 'earned' approx €45 (i.e. we are net €45 better off than if there was no solar install). In those 10 days there were 5 reasonable solar days and 5 duds. Not too shabby but too short a time period to make any conclusions but for a period between the 2 solstices it might be a good indication.
This also buys us an off grid system which will see us through the many power outages (sometimes for days) we experience every year.
I will likely need to replace the inverter within 10 to 15 years so that needs to be taken into account (current cost is ~€1200). There are very few other pieces of kit that will need replacement or servicing I reckon.
While the investment is indeed 'long term fixed' and there is no guarantee of FIT lasting at current or any levels, my view is that a lot of the returns are also guaranteed once the sun rises in the east and sets in the west.
Very similar to my own set up, though I paid a bit more than you did.
Can I ask how many kWh you have generated in the 10 days of March. .
Just shy of 242 kWhr
CuriousG10
New Member
- Messages
- 4
Thanks for your reply. This is the argument I am trying to figure out. Your previous electricity costs were 1K per year and you spend 10K and you expect a payback of that in less than 5 years. This just does not add up for me. Do you actually get money from the electricity provider?
That's the plan
I was a sceptic, but getting solar installation in a couple of weeks.
12 panels, 5.4kw, 10kw battery, €7800 net
Electricity bill quite low - circa 1400 a year.
Water is from oil system.
Fully expect €800 micro generation a year due to low daytime use and direct South facing roof. Expect about €600 savings on electricity assuming low solar in winter.
But also, the hot water will be from solar now, so likely €200-€300 oil saving.
It will also mean plentiful hot water, so might enjoy longer showers and relaxing long baths (with wine). Might use cooker more then often and actually use some cookery books I've gathered over the years.
Overall, even dialling down expectations, I reckon €1400 a year real money difference at an absolute minimum, but the other benefits have value too and, if we were selling, it's a strong selling point for a property.
12 panels, 5.4kw, 10kw battery, €7800 net
Electricity bill quite low - circa 1400 a year.
Water is from oil system.
Fully expect €800 micro generation a year due to low daytime use and direct South facing roof. Expect about €600 savings on electricity assuming low solar in winter.
But also, the hot water will be from solar now, so likely €200-€300 oil saving.
It will also mean plentiful hot water, so might enjoy longer showers and relaxing long baths (with wine). Might use cooker more then often and actually use some cookery books I've gathered over the years.
Overall, even dialling down expectations, I reckon €1400 a year real money difference at an absolute minimum, but the other benefits have value too and, if we were selling, it's a strong selling point for a property.
What saving?
For example (back of envelope calcs), suppose it takes 12 kWhr to heat 180l of water to 60 degC.
Using solar you will forego 12 times the FIT, say €0.20 per kWhr, so €2.40 to replace using maybe 1.5 litres of oil assuming 80% oil system efficiency. So little to no savings even in these times of oil price spikes.
You are, of course, correct if FIT goes to nothing.
After €800 micro generation, (couple ) tax is due, so the 18c fit becomes 9c net
But even if I decided to use the oil for water all year, then the micro generation would be higher - so whatever way you look, the net benefit would be in excess of the minimum I expect.
I like the sound of that, very similar to my own situation, have been thinking about it a bit since Christmas. Is this a countrywide installer or local to you? Have someone coming next week to look and quote, my roof is bitty as it has 5 velux in back of standard bungalow size so that was putting me off but I'll wait and see.